1. Technical Field
The present invention generally relates to a method of synthesizing colloidal nanoparticles. The present invention also relates to a system for synthesizing the same.
2. Background
Continuous flow-based micro-fluidic synthesis methods operate at steady state and offer superior control over reaction conditions such as reagent addition, mixing and temperature. Scale-up to higher throughputs is straightforward in principle, and involves parallel operation of multiple reactor units. Several research groups have leveraged on one or more of these advantages and successfully demonstrated the wet chemical synthesis of semiconducting, metallic, dielectric, magnetic and core-shell nano-particles. However, the high surface-to-volume ratios in continuous micro-fluidic reactors imply significant particle deposition and aggregation on micro-channel walls, which leads to rapid, irreversible particle deposition and thus degradation of product quality with time. Hence isolation of growing particles from the micro-channel walls becomes a requirement in these techniques.
Another method to form colloids is to use bulk-solution-phase methods. However, as reagent homogenization and chemical reaction proceed simultaneously in the reaction vessel, it becomes very difficult to control the final outcome. Hence, the synthesis of colloidal nanomaterials via bulk solution-phase methods remains a difficult and somewhat of an “art” even after the discovery of suitable chemical ingredients and all else remaining the same, there is much that is dependent on the “synthetic skills” of the chemist. Hence, this method is unreliable and does not produce consistent results.
As an alternative to bulk solution-phase synthesis, confinement of reagents in dispersed water drops of a water-in-oil micro-emulsion has been extensively studied. Such systems, where self-assembled surfactant micelles function as individual batch reactors have been used for the synthesis of a broad range of colloidal nano-materials. However, the scalability of this method is limited by the emulsification procedure employed and it is commonly not possible to control reagent dispensing at the scale of a single micelle.
An alternative approach involves the use of droplet micro-fluidics to overcome the above-mentioned drawbacks. The main drawback limiting the general applicability of such methods is the sensitive dependence of flow pattern on fluid properties such as interfacial tension. Fluid properties are usually dictated by the reagents required for synthesis, and are usually act independent design variables. Hence, it remains a challenge to decouple the dependence of flow patterns from the fluid properties. Further, such a method can result in fouling of the micro-fluidic device since the size of the droplets cannot be controlled adequately.
There is a need to provide a micro-fluidic device that overcomes, or at least ameliorates, one or more of the disadvantages described above.
There is a need to provide a method for colloidal synthesis that that overcomes, or at least ameliorates, one or more of the disadvantages described above.